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Biology subjects

Salas-Lloret, D.

Publications and source records attributed to Salas-Lloret, D..

3 recordsLinked to original sources

Immunometabolic reprogramming by LRH-1/NR5A2 pharmacological activation resolves inflammation in immune cells of type 1 diabetes mellitus individuals and improves human islet engraftment and function

The intricate etiology of type 1 diabetes mellitus (T1D), marked by a detrimental cross-talk between the immune system and insulin-producing {beta}-cells, has impeded effective disease-modifying therapies. The discovery that pharmacological activation of the nuclear receptor LRH-1/NR5A2 can reverse hyperglycemia in mouse models of T1D by attenuating the autoimmune attack coupled to {beta}-cell survival/regeneration, prompted us to investigate whether immune tolerization could be achieved in individuals with T1D by LRH-1/NR5A2 activation as well as improving islet function/survival after xenotransplantation in mice. Pharmacological activation of LRH-1/NR5A2 induced a coordinated genetic and metabolic reprogramming of T1D macrophages and dendritic cells, shifting them from a pro-to an anti-inflammatory/tolerogenic phenotype. Regulatory T-cells were also expanded resulting in the impediment of cytotoxic T-cell proliferation. LRH-1/NR5A2 activation enhanced human islet engraftment and function in hyperglycemic immunocompetent mice. In summary our findings demonstrate the feasibility of re-establishing immune tolerance within a pro-inflammatory environment, opening a new therapeutic venue for T1D.

cell biology↗

BRCA1/BARD1 ubiquitinates PCNA in unperturbed conditions to promote replication fork stability and continuous DNA synthesis.

Deficiencies in the BRCA1 tumor suppressor gene are the main cause of hereditary breast and ovarian cancer. BRCA1 is involved in the Homologous Recombination DNA repair pathway, and, together with BARD1, forms a heterodimer with ubiquitin E3 activity. The relevance of the BRCA1/BARD1 ubiquitin E3 activity for tumor suppression and DNA repair remains controversial and most efforts aimed to identify BRCA1/BARD1 ubiquitination substrates rely on indirect evidence. Here, we observed that the BRCA1/BARD1 ubiquitin E3 activity was not required for Homologous Recombination or resistance to Olaparib. Using TULIP2 methodology, which enables the direct identification of E3-specific ubiquitination substrates, we identified substrates for BRCA1/BARD1. We found that PCNA is ubiquitinated by BRCA1/BARD1 in unperturbed conditions independently of RAD18. PCNA ubiquitination by BRCA1/BARD1 avoids the formation of ssDNA gaps during DNA replication and promotes replication fork stability epistatically to BRCA1 S114 phosphorylation, addressing the controversy about the function of BRCA1/BARD1 E3 activity in Homologous Recombination.

molecular biology↗

SUMO Activated Target Traps (SATTs) enable the identification of a comprehensive E3-specific SUMO proteome.

Ubiquitin and ubiquitin-like conjugation cascades consist of dedicated E1, E2 and E3 enzymes with E3s providing substrate specificity. Mass spectrometry-based approaches have enabled the identification of more than 60,000 acceptor sites for ubiquitin and 40,000 acceptor sites for SUMO2/3. However, E3-to-target wiring is poorly understood. The limited number of SUMO E3s provides the unique opportunity to systematically study E3-substrate wiring. We developed SUMO Activated Target Traps (SATTs) and systematically identified substrates for eight different SUMO E3s, PIAS1, PIAS2, PIAS3, PIAS4, NSMCE2, ZNF451, LAZSUL(ZNF451-3) and ZMIZ2. SATTs enabled us to identify 590 SUMO1 and 1195 SUMO2/3 targets in an E3-specific manner. We found pronounced E3 substrate preference, even at the substrate isoform level. Quantitative proteomics enabled us to measure substrate specificity of E3s, quantified using the SATT index. Furthermore, we developed the Polar SATTs web-based tool (https://amsterdamstudygroup.shinyapps.io/PolaRVolcaNoseR/) to browse the dataset in an interactive manner, increasing the accessibility of this resource for the community. Overall, we uncover E3-to-target wiring of 1681 SUMO substrates, highlighting unique and overlapping sets of substrates for eight different SUMO E3 ligases.

molecular biology↗